/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.test.context.junit.jupiter;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.junit.jupiter.api.extension.ConditionEvaluationResult;
import org.junit.jupiter.api.extension.ExecutionCondition;
import org.junit.jupiter.api.extension.ExtensionContext;
import org.springframework.beans.factory.config.BeanExpressionContext;
import org.springframework.beans.factory.config.BeanExpressionResolver;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.GenericApplicationContext;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.util.Optional;
import java.util.function.Function;

/**
 * Abstract base class for implementations of {@link ExecutionCondition} that
 * evaluate expressions configured via annotations to determine if a container
 * or test is enabled.
 *
 * <p>Expressions can be any of the following.
 *
 * <ul>
 * <li>Spring Expression Language (SpEL) expression &mdash; for example:
 * <pre style="code">#{systemProperties['os.name'].toLowerCase().contains('mac')}</pre>
 * <li>Placeholder for a property available in the Spring
 * {@link org.springframework.core.env.Environment Environment} &mdash; for example:
 * <pre style="code">${smoke.tests.enabled}</pre>
 * <li>Text literal &mdash; for example:
 * <pre style="code">true</pre>
 * </ul>
 *
 * @author Sam Brannen
 * @author Tadaya Tsuyukubo
 * @see EnabledIf
 * @see DisabledIf
 * @since 5.0
 */
abstract class AbstractExpressionEvaluatingCondition implements ExecutionCondition {

    private static final Log logger = LogFactory.getLog(AbstractExpressionEvaluatingCondition.class);

    private static <A extends Annotation> Optional<A> findMergedAnnotation(
            AnnotatedElement element, Class<A> annotationType) {

        return Optional.ofNullable(AnnotatedElementUtils.findMergedAnnotation(element, annotationType));
    }

    /**
     * Evaluate the expression configured via the supplied annotation type on
     * the {@link AnnotatedElement} for the supplied {@link ExtensionContext}.
     *
     * @param annotationType       the type of annotation to process
     * @param expressionExtractor  a function that extracts the expression from
     *                             the annotation
     * @param reasonExtractor      a function that extracts the reason from the
     *                             annotation
     * @param loadContextExtractor a function that extracts the {@code loadContext}
     *                             flag from the annotation
     * @param enabledOnTrue        indicates whether the returned {@code ConditionEvaluationResult}
     *                             should be {@link ConditionEvaluationResult#enabled enabled} if the expression
     *                             evaluates to {@code true}
     * @param context              the {@code ExtensionContext}
     * @return {@link ConditionEvaluationResult#enabled enabled} if the container
     * or test should be enabled; otherwise {@link ConditionEvaluationResult#disabled disabled}
     */
    protected <A extends Annotation> ConditionEvaluationResult evaluateAnnotation(Class<A> annotationType,
                                                                                  Function<A, String> expressionExtractor, Function<A, String> reasonExtractor,
                                                                                  Function<A, Boolean> loadContextExtractor, boolean enabledOnTrue, ExtensionContext context) {

        Assert.state(context.getElement().isPresent(), "No AnnotatedElement");
        AnnotatedElement element = context.getElement().get();
        Optional<A> annotation = findMergedAnnotation(element, annotationType);

        if (!annotation.isPresent()) {
            String reason = String.format("%s is enabled since @%s is not present", element,
                    annotationType.getSimpleName());
            if (logger.isDebugEnabled()) {
                logger.debug(reason);
            }
            return ConditionEvaluationResult.enabled(reason);
        }

        String expression = annotation.map(expressionExtractor).map(String::trim).filter(StringUtils::hasLength)
                .orElseThrow(() -> new IllegalStateException(String.format(
                        "The expression in @%s on [%s] must not be blank", annotationType.getSimpleName(), element)));

        boolean loadContext = loadContextExtractor.apply(annotation.get());
        boolean evaluatedToTrue = evaluateExpression(expression, loadContext, annotationType, context);

        if (evaluatedToTrue) {
            String adjective = (enabledOnTrue ? "enabled" : "disabled");
            String reason = annotation.map(reasonExtractor).filter(StringUtils::hasText).orElseGet(
                    () -> String.format("%s is %s because @%s(\"%s\") evaluated to true", element, adjective,
                            annotationType.getSimpleName(), expression));
            if (logger.isInfoEnabled()) {
                logger.info(reason);
            }
            return (enabledOnTrue ? ConditionEvaluationResult.enabled(reason)
                    : ConditionEvaluationResult.disabled(reason));
        }
        else {
            String adjective = (enabledOnTrue ? "disabled" : "enabled");
            String reason = String.format("%s is %s because @%s(\"%s\") did not evaluate to true",
                    element, adjective, annotationType.getSimpleName(), expression);
            if (logger.isDebugEnabled()) {
                logger.debug(reason);
            }
            return (enabledOnTrue ? ConditionEvaluationResult.disabled(reason) :
                    ConditionEvaluationResult.enabled(reason));
        }
    }

    private <A extends Annotation> boolean evaluateExpression(String expression, boolean loadContext,
                                                              Class<A> annotationType, ExtensionContext context) {

        Assert.state(context.getElement().isPresent(), "No AnnotatedElement");
        AnnotatedElement element = context.getElement().get();
        GenericApplicationContext gac = null;
        ApplicationContext applicationContext;

        if (loadContext) {
            applicationContext = SpringExtension.getApplicationContext(context);
        }
        else {
            gac = new GenericApplicationContext();
            gac.refresh();
            applicationContext = gac;
        }

        if (!(applicationContext instanceof ConfigurableApplicationContext)) {
            if (logger.isWarnEnabled()) {
                String contextType = applicationContext.getClass().getName();
                logger.warn(String.format("@%s(\"%s\") could not be evaluated on [%s] since the test " +
                                "ApplicationContext [%s] is not a ConfigurableApplicationContext",
                        annotationType.getSimpleName(), expression, element, contextType));
            }
            return false;
        }

        ConfigurableBeanFactory configurableBeanFactory = ((ConfigurableApplicationContext) applicationContext).getBeanFactory();
        BeanExpressionResolver expressionResolver = configurableBeanFactory.getBeanExpressionResolver();
        Assert.state(expressionResolver != null, "No BeanExpressionResolver");
        BeanExpressionContext beanExpressionContext = new BeanExpressionContext(configurableBeanFactory, null);

        Object result = expressionResolver.evaluate(
                configurableBeanFactory.resolveEmbeddedValue(expression), beanExpressionContext);

        if (gac != null) {
            gac.close();
        }

        if (result instanceof Boolean) {
            return (Boolean) result;
        }
        else if (result instanceof String) {
            String str = ((String) result).trim().toLowerCase();
            if ("true".equals(str)) {
                return true;
            }
            Assert.state("false".equals(str),
                    () -> String.format("@%s(\"%s\") on %s must evaluate to \"true\" or \"false\", not \"%s\"",
                            annotationType.getSimpleName(), expression, element, result));
            return false;
        }
        else {
            String message = String.format("@%s(\"%s\") on %s must evaluate to a String or a Boolean, not %s",
                    annotationType.getSimpleName(), expression, element,
                    (result != null ? result.getClass().getName() : "null"));
            throw new IllegalStateException(message);
        }
    }

}
